As we all know, a brain-mapping test was conducted on Krishna, Dr. Rajesh Talwar’s compounder, at the Forensic Science Laboratory (FSL), Bangalore in connection with the murder of Aarushi and domestic help Hemraj in Noida. These tests gained popularity (and sparked a furor of debates) when they were used in the Rahul Mahajan and Sahil Zaroo drug abuse case and also on Abu Salem.

So what are these brain mapping and narco-analysis techniques of lie detection?

A minority of people (approximately 5 per cent) have the inherent ability of sniffing out deception. Therefore, the others have to resort to scientific methods to find the Pinocchio. One of these methods is using a lie detector. A lie detector involves the attaching of the polygraph to the suspect’s body. The polygraph measures physiological responses to stress, like increases in blood pressure, respiration rate and electrodermal skin response. As such, it has a major flaw that it can miss the cold-blooded liars who either don’t care that they’re lying, or don’t know that they are lying or have been trained to lie. Doubting the credibility of conventional lie–based detectors, there has been a need of more mature techniques in extracting the truth from the accused or the witnesses. Hence scientists resorted to ways of figuring out how the various parts of the brain function. This forms the basis of the techniques of brain mapping presently used which gives way to scientific interrogation.

In case of the Brain Mapping Test, also known as Brain fingerprinting, words and pictures associated with the crime, apart from irrelevant words and pictures are shown to the suspect on a computer screen. To measure his responses, electrical brain responses are recorded through a headband equipped with various sensors. A specific brain-wave response called a MERMER (Memory and Encoding Related Multifaceted Electroencephalographic Response) is obtained when the brain processes the noteworthy information it picks up, confirming that the suspect has information about the crime.

Another method used is the narco-analysis test. Here, the subject is injected with “truth” serum that induces him to give answers to specific questions. The serum ensures that his replies are restricted only to the happenings he is aware of. The technology at present is in its nascent stage in the country. It has been found that this method of interrogation is not free from partial contamination, with deception, delusion and fantasy having a role to play.

When it comes to scientific issues, each of the methods is met by limitations. The Central Intelligence Agency, that extensively studied truth serums emphasized in its testimony at a United States Senate hearing in 1977 that there was no guarantee at all whether questioning a drugged subject would produce the truth. When it comes to Brain Mapping, it determines presence of specific information in the brain, but it cannot tell how it got there. It means that at times it fails to distinguish between the perpetrator of a crime and an eyewitness. In terms of legality, it is believed in most democracies that “the forcible extraction of information from an accused by pharmacological means is recognized to be as violative of his or her rights as extracting information by physical brutality would be.”

After going through various research articles I can conclude that these methods of lie detection are still in their primitive stages, and are backed by very littleforensic experience or evidence. The research literature on it is based mostly on laboratory studies under artificial circumstances. Hence I feel that the Indian Agencies should not only focus on developing methods that rely on forensic expertise rather than resorting to methods which have not proven their accuracy. At the same time, it is important to consider the legal and ethical aspects as well. Thus it is essential to use these tests (if no alternative exists) judiciously.